JPH08291423A - Inorganic material filled fiber, its production and concrete molding produced by using the fiber - Google Patents

Abstract

PURPOSE: To obtain the subject fiber having excellent concrete-reinforcing function and useful for producing a concrete molding having improved shock resistance and flexural strength by compounding a polyolefin fiber with inorganic fine particles such as silicon oxide in a specific state. CONSTITUTION: This fiber is produced by dispersing inorganic fine particles shown below near the surface layer of a polyolefin fiber and making a part of the particles expose from the fiber surface. The inorganic fine particles comprise an oxide, carbonate or sulfate of at least one kind of element selected from a group of silicon, aluminum, calcium and magnesium, and they optionally contain oxide of sodium or potassium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin fiber filled with an inorganic material, a method for producing the same, and a concrete molded product using the same. More specifically, the present invention relates to a polyolefin fiber having an increased affinity for concrete by being filled with an inorganic material, a method for producing the same, and a concrete molded body reinforced by the fiber having improved impact resistance and bending strength.

[0002]

2. Description of the Related Art Conventionally, as a fiber for reinforcing concrete,
It is widely practiced to mix synthetic fibers such as nylon, vinylon and polypropylene into concrete. Among them, polypropylene fiber is excellent in alkali resistance under heating and excellent in strength as compared with other fibers, and is suitable for improving impact resistance of concrete products, and therefore is still widely used at present. However, since polyolefin fibers made of polypropylene, polyethylene, etc. have inherently high hydrophobicity and poor affinity with cement particles, fine powder of calcium carbonate is added to polypropylene fibers, and the interface is further added to the fiber surface. There is known one to which an activator is attached (JP-A-5-44163).

[0003]

However, the technique disclosed in Japanese Unexamined Patent Publication No. 5-44163 is a polyolefin fiber containing fine powder of calcium carbonate, but the surface shape is fine powder of calcium carbonate. However, since the protruding portion is covered with the polyolefin film, the calcium carbonate fine powder does not exert the binding force with the cement component. Therefore, it has a drawback that it is not yet used as a concrete molded product having impact resistance and bending strength. In particular, there is a problem in that the flexural strength is insufficient, even though the flexural strength is essential for the concrete molded body during storage and transportation of the sediment.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors further rubbed the inorganic fine particles exposed formally on the fiber surface to further rub the inorganic fine particles. The inventors have found that the desired object can be achieved by obtaining a polyolefin fiber having a surface exposed to the surface, and have completed the present invention.

The present invention has the following configuration. (1) An oxide, carbonate or sulfate of at least one element selected from the group consisting of silicon, aluminum, calcium and magnesium, and optionally sodium.
Inorganic fine particles containing inorganic oxides, which also contain potassium oxide, are dispersed in the vicinity of the surface layer of the polyolefin fiber and are partially exposed from the fiber surface. (2) The inorganic material-filled fiber according to item (1), wherein the polyolefin fiber is a sheath-core type composite fiber, inorganic fine particles are dispersed in the sheath component, and a part is exposed from the fiber surface. (3) The inorganic material-filled fiber according to item (1) or (2), wherein the polyolefin-based fiber has a non-circular modified cross section. (4) Surface exposure coefficient of inorganic fine particles (ratio of the area occupied by exposed inorganic fine particles to the fiber surface area) is 5%.
The inorganic-filled fiber according to item (1) or (2) above. (5) MFR50-200 polypropylene resin 10
70 wt%, polypropylene resin 90 with MFR 1-30
Characterized in that a polypropylene resin consisting of ˜30% by weight and a sheath part consisting of 10 to 40% by weight of the total amount of the polypropylene resin and an inorganic fine particle, and a core part consisting only of a polyolefin resin are melt-spun. Manufacturing method of polyolefin fiber. (6) A concrete molded body formed by using the inorganic-filled fiber according to the items (1) to (4). (7) The concrete molded body according to the item (6), wherein the strength of pulling out the reinforcing fiber from the concrete molded body is 80% or more of the yarn strength. The term “inorganic substance-filled fiber” as used in the present invention means an inorganic substance-filled fiber in which the inorganic fine particles are exposed on the fiber surface.

The polyolefin fiber referred to in the present invention means
A polyolefin resin represented by α-olefin resin, and as the polyolefin resin, polypropylene, a crystalline copolymer mainly composed of propylene with other olefins, high density polyethylene, medium density polyethylene, low Density polyethylene, linear low density polyethylene,
A copolymer polypropylene etc. can be illustrated. Among these polyolefin resins, at least one selected from high-density polyethylene, low-density polyethylene, linear low-density polyethylene and polypropylene is preferably used. In particular, polypropylene fibers are preferable, and among them, highly crystalline polypropylene fibers are more preferably used.

The inorganic fine particles referred to in the present invention specifically include silicon oxide (SiO ₂ system: quartz powder, silica stone powder,
As diatomaceous earth, silica fume, natural silica, pearlite,) aluminum oxide, magnesium oxide (or carbonate) (MgCO ₃ system: dolomite, magnesia),
Calcium oxide and calcium carbonate can be mentioned. In addition, S
iO ₂ · Al ₂ O ₃ system: Kaolin, clay, mica, sericite,
SiO ₂ · Al ₂ O ₃ · K ₂ O · Na ₂ O system: zeolite, sericite, SiO ₂ · Al ₂ O ₃ system: kaolin clay, kaolin, calcined kaolin (metakaolin), montmorillonite, SiO ₂ · MgO system: Asbestos, mica, talc, sepiolite, vermiculite, SiO ₂ · CaO series: wollastonite, calcium silicate, calcium sulfate, SiO ₂ · Al ₂ O
₃ · MgO-based: attapulgite, and the like. Of these, compounds containing both magnesium carbonate, silicon oxide and aluminum oxide are particularly preferable. Regarding the size of the inorganic fine particles, in the case of kneading, those having a diameter of 10 μm or less are preferable because the spinnability during spinning is good.

Since the above-mentioned inorganic fine particles exert their effect in terms of binding force only when they are exposed on the surface of the polyolefin fiber, it is an important requirement how they are present on the fiber surface. However, mixing inorganic fine particles into the fiber leads to a reduction in the strength of the fiber. Further, even when the inorganic fine particles were added, they were not exposed because the surface was covered with the polyolefin resin, and they were physically caught, but did not contribute to the binding force. Therefore, a method of exposing the inorganic fine particles on the surface of the fiber is required. 2 as the method
There is a method, one is method A in which the above-mentioned inorganic fine particles are sprayed onto a molten polyolefin resin during spinning, and the other is to add the above inorganic fine particles to the polyolefin resin and rub the fiberized one. Method B is a method in which the polyolefin resin covering the inorganic fine particles is scraped off, and either method may be used.

In the method A, since the inorganic fine particles are sprayed directly on the fiber surface, unlike the method in which they are added into the fiber, they are dispersed in the vicinity of the surface layer of the fiber and a part is exposed from the surface. Moreover, there is no concern about deterioration of spinnability and filter life during spinning due to the inorganic fine particles,
The inorganic fine particles having a large diameter can be used.
In the method B, the inorganic fine particles are surely contained in the olefin resin, so that the inorganic fine particles do not fall in the steps up to fiber formation, particularly in the stretching step. However, there is a problem that the filter life is shortened due to the clogging of the inorganic fine particles during spinning. In order to extend the filter life, it is necessary to reduce the added amount of the inorganic fine particles as much as possible.

Methods B include method B-1 in which the above-mentioned inorganic fine particles are added only to the dispersed sheath-core type sheath, and method B has a small molecular weight (M
B-2 method in which the inorganic fine particles are present only in the surface layer of the fibers by mixing the pelletized inorganic fine particles with the (large FR) olefin resin into an olefin resin having a large molecular weight (small MFR) And B-3 method which combines both. When a polymer having a large molecular weight and a polymer having a small molecular weight are blended and spun, a fiber having a small molecular weight is present on the fiber surface due to the surface tension. It is considered that this exposes the surface of the inorganic fine particles kneaded into the polyolefin resin, which is a feature of the present invention.

That is, a pellet obtained by kneading the above-mentioned inorganic fine particles into a polyolefin resin having a small molecular weight is blended with a polyolefin resin having a large molecular weight and spun to give a large amount of the polyolefin resin having a small molecular weight on the fiber surface. It is considered that the above-mentioned inorganic fine particles that have been kneaded together are collected in the fiber surface layer. A fiber in which the inorganic fine particles are exposed from the fiber surface can be manufactured by finally rubbing the inorganic fine particles collected in the surface layer of the fiber for the purpose of exposing. The molecular weight of polyolefin resin with a small molecular weight is MFR (230
Measured in ° C. The same applies hereinafter) 50 to 200, and the polyolefin resin having a large molecular weight has a molecular weight of 1 to 30. The mixing ratio of both is 10 to 70% by weight in the former case. Spinning can be performed by a usual melt spinning method. Although it is possible to use an ordinary die having a circular cross section, it is also possible to use a die having an irregular cross section such as a Y-shape, a cross shape, a swastika type, a flat type, a corrugated shape, or a multi-groove type if necessary. In the case of the modified cross section fiber, the specific surface area can be increased as compared with the circular cross section.

Method B-1 is a method in which the core is made of only the polyolefin resin and the inorganic fine particles are added to the polyolefin resin of the sheath. In this case, the polyolefin in the core maintains spinnability and the inorganic fine particles are added only to the sheath, so that the amount of addition can be reduced. Method B-2 is a method in which the inorganic fine particles are pelletized with an olefin resin having a small molecular weight, and the pelletized inorganic fine particles are mixed with an olefin resin having a large molecular weight so that the inorganic fine particles are present only in the surface layer of the fiber. However, the inorganic fine particles present in the central portion of the melted olefin resin move toward the surface layer until they solidify, so that they can be effectively used.

The B-1 method in which the inorganic fine particles are added only to the sheath-core type sheath, and the inorganic fine particles are pelletized with an olefin resin having a small molecular weight to obtain an olefin resin having a large molecular weight. The B-3 method, which is a combination of both the B-2 method in which the inorganic fine particles are present only in the surface layer of the fiber by mixing, can further reduce the amount of addition of the inorganic fine particles because the advantages of both methods are incorporated. This is the most preferable method because it has the advantage of extending the filter life. That is, according to the B-3 method, the inorganic fine particles in the vicinity of the surface layer during spinning can be concentrated on the surface before the olefin resin solidifies. Finally, by rubbing these polyolefin fibers obtained by the method B, the inorganic-filled fibers which are the object of the present invention can be produced.

When the fiber is thick (10 d / f to 2000 d / f)
In addition, since it is possible to hold the above-mentioned inorganic fine particles having a large diameter as well as a small diameter, the method A is desirable, and when the fiber is thin (1 d / f to 10 d / f), the above-mentioned inorganic fine particles having a large diameter can be retained. Since it is difficult to retain the object, it is desirable to use the inorganic fine particles having a small diameter, and the method B is desirable from the environmental point of view in consideration of scattering of fine particles. Method B-1 or B-
In the 3rd method, it is used in the form of a sheath-core type composite fiber, and the same or different polyolefin-based resin described above can be used as the polyolefin-based resin constituting the sheath or the core. The composite ratio (weight ratio; the same applies below) is 30 /
70-70 / 30, preferably 40 / 60-60 / 4
0, more preferably 45/55 to 55/45. If the composite ratio of the sheath portion of the composite fiber is 70% or more, the tensile strength of the fiber is insufficient, and sufficient bending strength as a concrete molded body cannot be obtained. On the other hand, if it is less than 30%, the productivity is deteriorated due to the balance of the sheath-core extruder, which is not preferable.

The surface exposure coefficient of the inorganic fine particles is a factor indicating how much the inorganic fine particles are exposed on the fiber surface. The inorganic fine particles exposed on the surface of the fiber have an affinity with concrete, and since this affinity reinforces the concrete, it is a very important factor as a fiber for reinforcing concrete. Specifically, the side surface of the fiber surface is photographed using an electron microscope,
It can be calculated by the following formula by analyzing the image. (Area occupied by the inorganic fine particles exposed from the fiber surface) / (Fiber surface area occupied in the field of view) x 100 (%) When the surface exposure coefficient obtained by the above calculation formula is 5% or more, it bonds with concrete. Although the effect of force can be obtained, it is preferably 10%, more preferably 20% or more. As a result, the pull-out resistance strength is improved, whereby the bending strength and impact strength of concrete are improved, and the desired concrete reinforcement can be achieved.

The physical properties of the concrete molding of the present invention are greatly influenced by the denier and cut length of the concrete reinforcing fiber. The denier of the concrete reinforcing fiber is preferably 1 to 2000 denier. It is more preferably 2 d / f to 100 d / f, and even more preferably 5 d / f to 30 d / f. If it is less than 1 denier, the fiber strength cannot withstand when stress is concentrated, and it is not sufficient. If it exceeds 2000 denier, it becomes difficult to uniformly disperse the concrete and the fibers, and it becomes easy to form a portion having low impact resistance and low bending strength. The cut length is preferably 3 to 15 mm. If the cut length is less than 3 mm, the fibers do not intersect, so that the impact strength of the concrete becomes insufficient, and if the cut length exceeds 15 mm, the fibers are entangled with each other and the dispersion becomes poor, so that it becomes difficult to uniformly disperse the concrete and the fibers. It becomes easy to form a portion having low impact resistance and low bending strength.

The heat-adhesive conjugate fiber used in the composite molded article of the present invention is preferably a non-crimped linear one because the fibers are not entangled with each other and are easily dispersed. In the fiber for reinforcing concrete of the present invention, the inorganic fine particles are 10
It is desirable that the content be ˜40% by weight. In this case, when only the sheath portion is filled, the percentage of only the sheath portion is shown, and when the whole fiber is filled, the percentage of the whole fiber is shown. If the content of the inorganic fine particles is less than 10% by weight, the impact resistance and bending strength of the concrete molded body are not sufficient. If the content of the inorganic fine particles exceeds 40% by weight, the filter life during spinning is shortened, which is not desirable. Further, the fiber of the present invention is added in an amount of 0.01 to 10% by weight of the total cement slurry, and further cement, water, if necessary, rock, asbestos, pulp or the like to prepare a cement slurry, which is dried according to a conventional method, The concrete molded product of the present invention can be obtained by curing. In the concrete molded product of the present invention, it is preferable that the fiber having excellent pull-out strength of the filled fiber is 80% or more of the tensile strength of the fiber, which is considered to be excellent in affinity with concrete.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the invention is not limited to the following examples and comparative examples as long as the gist of the present invention is not exceeded. The surface exposure coefficient, pullout resistance strength, bending strength, and Charpy impact strength used in each example were measured as follows. Unless otherwise specified in spinning, a die for circular cross section was used. << Surface Exposure Coefficient >> The side surface of the fiber surface was photographed using an electron microscope and the image analysis was performed to obtain the exposed area of the inorganic fine particles / the fiber surface area occupying in the visual field, which was expressed as an area percentage. (N = 10) << Pull-out resistance strength >> The pull-out resistance strength is obtained by adjusting the PP fiber of the surface layer portion of the concrete molded body to the Push-manufactured by Imada Co., Ltd.
The maximum load when one end of the PP fiber was pulled out was set as the pull-out strength by hooking with a pull-scale hooking tool. (N = 20) << Bending strength >> Bending test It was measured according to JIS-A-1408. <Charpy impact strength> Charpy impact strength test JIS
-Measured according to B-7722. [Examples 1 to 4 and Comparative Example 1] Using the inorganic fine particles and polypropylene shown in Tables 1 and 2, a single fiber was heated to 280 ° C.
Melt spinning, spraying various inorganic fine particles with various average particle diameters directly under the spinneret, stretching 4 times at 110 ° C., 10 m
Cut to m. The fineness of the drawn yarn, the strength and elongation, and the pulling resistance strength from concrete were measured, and the results are shown in Table 4.

[Examples 5 to 8, Example 13, Comparative Examples 2 to 2]
3] Polypropylene shown in Tables 1 to 3 and a sheath-core type having a single fiber and an area ratio in the fiber cross section of 50/50 using pellets obtained by kneading the polypropylene with various inorganic fine particles having various average particle sizes The pellets were used as the sheath component of the composite fiber, melt-spun at 280 ° C, and
After double stretching, the fiber surface was rubbed by passing through a fixed roll and cut into 10 mm. The fineness of the drawn yarn, the strength and elongation, and the pulling strength from the concrete were measured, and the results are shown in Table 5. In Example 13, a Y-shaped mouthpiece was used.

[Examples 9 to 12, Comparative Example 4] Example 3,
24 g each of 6 to 8 and Comparative Example 1 short fibers, 7.
Pour into 2 liters of tap water and, with stirring, ordinary Portland cement 680 g, asbestos 40 g, pulp 8
g and serpentine powder 48 g were sequentially added and mixed to prepare an 8-liter cement slurry. Further, 20 ml of a 0.02 wt% liquid of a flocculant IKE FLOCK (trade name: manufactured by Ichikawa Kaori Co., Ltd.) was added, and after pouring this slurry into a mold container, it was dehydrated through a wire mesh of 60 mesh, and a flat plate having a thickness of 5 mm. A semi-plastic product in the form of a solid was obtained. The product was allowed to stand at room temperature in a wet state for 28 days, and after natural curing, the concrete product was evaluated. The results are shown in Table 6 as Examples 9 to 12 and Comparative Example 4, respectively.

As a result of the experiment, as shown in Tables 4 and 5, with respect to all of the blanks excluding Comparative Example 1 sprayed with the inorganic fine particles and the ones rubbed after kneading the pellets, the pull-out resistance strength is the yarn strength. It was 80% or more of the (tensile strength of the yarn properties). On the other hand, the pull-out strength was very small even though the inorganic fine particles were not sprayed. In Comparative Examples 2 and 3 shown in Table 5, the inorganic fine particles having a diameter of 10 μm were used, and the spinnability was poor. Therefore, there is no data for items below the surface exposure coefficient. Since stable spinning could not be performed, it can be seen that the one having a diameter of 10 μm cannot be used in the kneading method. Comparing Examples 5, 13 and 6 with each other, it can be seen that in the case of the single fiber, the tensile strength of the yarn is lower than that of the composite fiber in which the inorganic fine particles are added only to the sheath portion. or,
Comparing Examples 5 and 13 with each other, Example 1 having a Y-shaped cross section
The pull-out resistance of No. 3 is stronger than that of Example 5. Comparing Examples 7 and 8, Example 8 using the pellets using the low molecular weight polypropylene has a larger surface exposure coefficient. Therefore, by using the pellets using the low molecular weight polypropylene, It was found that the inorganic fine particles are effective for collecting on the surface layer. Comparing Examples 11 and 12, Example 12 using pellets made of polypropylene having a small molecular weight is superior in both bending strength and impact strength. Therefore, a large amount of inorganic fine particles are to be produced on the surface. Was found to be effective, and it was found to be effective to use pellets made of polypropylene having a small molecular weight.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

[Table 6]

[0028]

INDUSTRIAL APPLICABILITY In the inorganic-filled fiber of the present invention, the inorganic fine particles are dispersed in the vicinity of the surface layer of the polyolefin-based fiber, and part of it is exposed. Excellent effect. The fiber of the present invention can be efficiently produced by the production method of the present invention. Further, the concrete of the present invention is excellent in bending strength and impact strength because it is filled with the fibers of the present invention having good affinity.

Claims (7)

[Claims] 1. An inorganic fine particle comprising an oxide, carbonate or sulfate of at least one element selected from the group consisting of silicon, aluminum, calcium and magnesium, and optionally containing oxides of sodium and potassium. But,
An inorganic-filled fiber characterized in that it is dispersed in the vicinity of the surface layer of a polyolefin fiber, and part of it is exposed from the fiber surface. 2. The inorganic-filled fiber according to claim 1, wherein the polyolefin-based fiber is a sheath-core type composite fiber, inorganic fine particles are dispersed in the sheath component, and a part thereof is exposed from the fiber surface. . 3. The inorganic-filled fiber according to claim 1, wherein the polyolefin fiber has a non-circular irregular cross section. 4. Surface exposure coefficient of inorganic particulate matter (ratio of area occupied by exposed inorganic particulate matter in fiber surface area)
Is 5% or more, and the inorganic-filled fiber according to claim 1 or 2. 5. A polypropylene resin comprising 10 to 70% by weight of a polypropylene resin having an MFR of 50 to 200 and 90 to 30% by weight of a polypropylene resin having an MFR of 1 to 30, and 10 to 40% by weight of the total amount of the polypropylene resin and inorganic fine particles. A method for producing a polyolefin fiber, which comprises melt-spinning a sheath made of a material and a core made of a polyolefin resin only. 6. A concrete molded body formed by using the inorganic-filled fiber according to any one of claims 1 to 4. 7. The concrete formed body according to claim 6, wherein the pull-out resistance strength of the reinforcing fiber from the concrete formed body is 80% or more of the yarn strength.